1. Field of the Invention
The present invention relates to the conversion of paraffins to olefins while suppressing undesirable cracking. In particular, the invention provides for the dehydrogenation of paraffin hydrocarbon using zeolite catalysts modified with a Group IA modifier and having incorporated therewith a transition metal component such as Zn.
2. Background of the Invention
The use of aluminosilicate zeolites such as ZSM-5 for the cracking of paraffin hydrocarbons is known. See, for example, U.S. Pat. No. 3,140,249.
The modification of a zeolite such as ZSM-5 by treatment with phosphorous and with the further incorporation therein of a transition metal such as zinc is known. See U.S. Pat. No. 3,972,832. When used for the conversion of a paraffin such as n-hexane cracking to lower olefins and paraffins was achieved.
The preparation of low acidity zeolites such as the sodium form of ZSM-5 and the use of those materials in the conversion of hydrocarbons is known. U.S. Pat. No. 4,263,129 shows the preparation of such catalysts including catalysts also containing a hydrogenation component such as cobalt-molybdenum or nickel-tungsten. The catalysts are described as effective in hydrocracking and result in lower yields of light gaseous hydrocarbons.
U.S. Pat. No. 3,899,544 describes the preparation of modified ZSM-5 catalysts by incorporating a limited amount of a Bronstead or Lewis base such as sodium therein. Hydrogenation/dehydrogenation components such as zinc and cadmium can also be incorporated in the catalysts. The use of catalysts for the conversion of alcohols and ethers to hydrocarbons is taught.